Ankhimera

Three-Headed. The ankhimera has advantage on Wisdom (Perception) checks and on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.

Multiattack. The ankhimera makes three attacks: one with its Ankheg's Bite, one with its Dragon's Bite, and one with its Horns. When its Acid Spray is available, it can use Acid Spray in place of its Ankheg's Bite. When its Cold Breath is available, it can use Cold Breath in place of its Dragon's Bite. However, it can't use both Acid Spray and Cold Breath on the same turn.

Ankheg's Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) piercing damage plus 3 (1d6) acid. If the target is a Large or smaller creature, it is grappled (escape DC 14). Until this grapple ends, the ankhimera can only use its Ankheg's Bite attack on the grappled creature and has advantage on attack rolls to do so.

Dragon's Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 15 (2d10 + 4) piercing damage plus 4 (1d8) cold.

Horns. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 10 (1d12 + 4) bludgeoning damage.

Acid Spray (Recharge 6). The ankheg head spits acid in a line that is 30 feet long and 5 feet wide, provided that it has no creature grappled. Each creature in that line must succeed on a DC 15 Dexterity saving throw, taking 21 (6d6) acid damage on a failed save, or half as much damage on a successful one.

Cold Breath (Recharge 6). The dragon head exhales an icy blast in a 15-foot cone. Each creature in that area must succeed on a DC 15 Constitution saving throw, taking 31 (7d8) cold damage on a failed save, or half as much damage on a successful one.